As dietary supplement, (−)-Hydroxcitic acid (HCA) is an effective agent to any weight management program. Allison et al. (Crit. Rev. Food Sci. Nutr. 2001, 41, 1-28) has reviewed the use of HCA as one of the alternative treatments for weight loss. The derivatives of HCA have been incorporated into many pharmaceutical preparations in combination with other ingredients for the purpose of enhancing weight loss, cardioprotection, correcting the conditions of lipid abnormalities and endurance (Jena et al., 2002, J. Agric. Food Chemistry, 50, 10-22). So far HCA has been found in the fruits of certain species of Garcinia, which includes G. cambogia, G. indica, G. atroviridis and G. cowa (Lewis, Y. S. 1969, Methods in enzymology, 13, 613-623; Jena et al., 2002, J. Agric. Food Chemistry, 50, 10-22). The chemistry and biochemistry of HCA has been discussed recently (Jena et al., 2002, J. Agric. Food Chemistry, 50, 10-22). During extensive animal studies, HCA has been proven to effectively curb appetite, suppress food intake, increase the rates of hepatic glycogen synthesis, reduce fatty acid synthesis and lipogenesis and decrease body-weight gain. Garcinia (Family: Guttiferae) is a large genus of polygamous trees or shrubs, distributed in the tropical Asia, Africa and Polynesia. It consists of 180 species, out of which about 30 species are found in India. G. pedunculata and G. cowa are grown in Northeastern parts of India and Andaman Islands. In Assam G. cowa is often cultivated in homesteads for its acid fruits (The Wealth of India, 1956). The fruits from both the species of Garcinia are not palatable due to their strong acid taste. In Assam the sun dried slices of the fruits are used for culinary purposes and as folk medicine.
Reference may be made to the commercial samples of Garcinia cambogia extracts, where the HCA is present as its calcium salt (Sawada, et al, 1997, Nihon yukagaka kaishi, vol, 1467-1474). But the excess calcium reduces the solubility and subsequently bioavailability when it is compared to the liquid extract.
Another reference may be made to the Ashok kumar., Ravindranath, B., and Balasubramamanvam (U.S. Pat. No. 656,314, 1996). This process involves water extraction, followed by passing through ion exchange resins and decolorisation by using activated charcoal and finally concentration by using vacuum evaporation. The main drawback of this method is the thermal process and also it involves too many unit operations for obtaining the final product.
Reference may be made to Majeed et al. (Majeed, M., Badmaev, V and Rajendran, R. U.S. Pat. No. 5,783,603, 1998), wherein the preparation of potassium hydroxycitrate from Garcinia fruit was reported. It involves the extraction of Garcinia fruit using alkyl alcohol, the extract was treated with potassium hydroxide and refluxed to form potassium hydroxycitrate precipitate. The main drawback of this method is the potassium salt is hygroscopic. Further, HCA is not available in natural state, limiting its bioavailability and versatile applicability for pharmaceutical purposes.
It may be noted that all these references are mentioned above HCA derivatives preparations. But, there is no report on non-thermal process for concentrating of HCA and also in its native (not as derivatives) form.